The Mission speakers from the early to mid-80s would be a good match for that Marantz. IIRC, the model 770 was a very good speaker. I also liked the KEFs from around that time period, 103s would be an excellent monitor for you. Also consider the ADS 710s or 810s from that period, they were very good speakers (get the ones with the metal grills)...
ADS 810s on eBay - very nice!
http://cgi.ebay.com/ADS-L810-Vintage-Speakers-w-Stands-Rare-200-watt_W0QQitemZ320233725495QQihZ011QQcategoryZ14993QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
KEF 103.2 on Audiogon, superb-sounding speakers!
http://cls.audiogon.com/cgi-bin/cls.pl?spkrmoni&1211989238
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ADS 810s on eBay - very nice!
http://cgi.ebay.com/ADS-L810-Vintage-Speakers-w-Stands-Rare-200-watt_W0QQitemZ320233725495QQihZ011QQcategoryZ14993QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
KEF 103.2 on Audiogon, superb-sounding speakers!
http://cls.audiogon.com/cgi-bin/cls.pl?spkrmoni&1211989238
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